This invention relates generally to an all solid state lithium battery, and more particularly to an all solid lithium battery of the type in which a lithium alloy layer is disposed between a solid electrolyte and a lithium anode.
A lithium (Li) electrode in conventional all solid state lithium batteries (hereinafter called simply the "lithium battery") is formed by either bonding directly a lithium foil to a solid electrolyte or by forming the lithium foil by evaporation on the solid electrolyte. In the Li anode of this kind, however, with the increase in the discharge current density of a battery, the quantity of consumed Li on the interface between the solid electrolyte and the Li anode exceeds the quantity supplemented by the diffusion of the Li atoms so that voids are formed in the Li anode on the interface between the solid electrolyte and the Li anode and hence the Li anode peels off. One of the methods of solving this problem is described in T. R. Jow and C. C. Liang, Solid State Ionics, 9, 10, 695 (1983), "Interface between Solid Anode and Solid Electrolyte-Effect of Pressure on Li/LiI (Al.sub.2 O.sub.3) Interface". This method brings the Li anode into constant and close contact with the solid electrolyte by an external pressure, crushes and extinguishes the voids that are formed with the increase in the discharge current density of the battery, and keeps a satisfactory contact between the solid electrolyte and the Li anode.
However, this method has the problem that a mechanism for applying constantly and continuously a large pressure of at least 400 kg/cm.sup.2 to the battery is necessary in order to keep the satisfactory interface contact between the solid electrolyte and the Li anode consequently, the method is not entirely suitable for reducing the size or thickness of the Li battery.